Resilient paper covers for containers and method of manufacture



March 31, 1959 2,879,935

P. H.- CARTER RESILIENT PAPER COVERS FOR CONTAINERS AND Filed March 13, 1957 METHOD OF MANUFACTURE v 2 Sheets-Sheet 1 INVENTOR. PAUL. CARTER 'ATTORN EY- P. H. CARTER RESILIENT PAPER COVERS FOR CONTAINERS AND March 31, 1959 Filed March 13, 1957 METHOD OF MANUFACTURE 2 Sheets-Sheet 2 FIG. I l.

PAUL CARTER INVENTOR ATTOR N EY;

United States Patent RESILIENT PAPER FOR CONTAINERS AND METHODOF MANUFACTURE Paul H. Carter, Baltimore, Md., assignor to The Maryland Cup Company, Baltimore, Md., a corporation of Maryland Application March 13, 1957, Serial No. 645,805

2 'Claims. (Cl. 229-43) This invention relates to covers or closures and it is more particularly concerned with the snap-on type of closures made of paper or similar fibrous material for containers, the mouths of the containers having beaded rims.

The devising of suitable covers of the type mentioned has, over a long period, been the subject of much research and study. In general, these covers are in the form of a flat disc with an annular dependent flange adapted to engage and encircle the beaded rim.

In order for these covers or lids to function properly, it is necessary that the annular flange have a sufiicient resilience to permit a sufficient degree of expansion thereof as it is pressed into position and that this resilience be effective under varying conditions of atmospheric humidity to provide a sealing pressure between the rim and the bead. This is particularly important in the case of the smaller size containers because of the fact that paper has a very small degree of stretchability and only in very large containers can the natural stretch of the rim of the ordinary paper lid be sufilcient to permit it to function properly. The amount of stretch required for a small size container is substantially the same as for a large size container, the difficulty being that there is less paper in the smaller size lids and hence the total permissible stretch of the lid rim is smaller in the smaller sizes than in the larger sizes.

To overcome this deficiency particularly, in the smaller sizes of containers, various devices have been restored to, including such drastic steps as providing radial slits in the flanged portion to permit a springyaction.

It is apparent that without a sufilcient amount of resilience, the beaded edge of the container would either become damaged when the lid was placed thereabout, or there would be insufficient pressure between the flange and the rim of the container, thereby giving rise to conditions of leakage of the container contents.

The general object of the present invention is the provision of a cover or lid of the type mentioned which is equally effective in small as well as large sizes.

Another object of the invention is the provision of such a lid which does not require a weakening of the lid structure or a loss of sealing effectiveness such as where slits are provided.

A further object of the invention is the provision of a lid of the type mentioned which is quantitatively economical of materials used and which can be rapidly manufactured with conventional tools and equipment.

A further object of the invention is the provision of a method of manufacturing such covers.

These and other objects, advantages and features of the invention will appear more fully from the following description considered together with the accompanying drawing.

In the drawing:

Fig. 1 is a perspective view of a paper container and a 7O lid as an embodiment of th1s invention in place thereon.

Fig. 2 is a section along the line 2--2 of Fig. 1.

Patented Mar. 31, 1959 Fig. 3 is a view similar to Fig. 2 with the lid in the act of being placed on the cup, the final position of the lid and cup being shown in dotted lines.

Fig. 4 is a plan view of a circular blank from which the lid is made.

Fig. 5 is a cross sectional view along the line 5-5 of Fig. 4.

Fig. 6 is a plan view of the same blank after being subjected to the first step in the process of forming a lid therefrom in accordance with this invention.

Fig. 7 is a section along the line 7-7 of Fig. 6.

Fig. 8 is a plan view of the same blank in the course of being subjected to a further step in the process of forming the lid.

Fig. 9 is a section along the line 99 of Fig. 8.

Fig. 10 is a top plan view of the finally formed lid.

Fig. 11 is a section along the line 1111 of Fig. 10.

Referring with more particularity to the drawing in which like numerals designate like parts throughout the several views, the embodiment comprises a cover it) having a flat top 21 and a dependent annular flange 22 adapted to encircle the beaded rim 23 about the mouth of a paper cup 24.

The flange 22 is formed of an annular marginal area of a flat blank disc 25 of the usual paperboard or card board of which lids of this general type are customarily made. The marginal area 26 is provided with a plurality of radial creases or corrugations 27 in spaced circumferential relation as shown in Fig. 6 as a first step in the formation procedure. At the same time, the marginal area is tilted at an angle to the remaining flat top portion 21, as shown in Fig. 7.

To retain these creases, the marginal area is then subjected to an endwise compression for the purpose of crushing it which results in a multiplicity of random circumferential folds or Wrinkles 28 (see Figs. 8 and 9). This compression is continued, the While moving the marginal area to a position substantially at right angles to the top portion 21, thus completing the formation of the resilient flange (Figs. 10 and 11). The pressure may be applied by any suitable die press (not shown) and the flange is preferably shaped to provide an inwardly projecting annular hump or lip 29 on the inner wall about midway between the top 21 and the bottom edge 30, thereby providing a camming surface 31 on the bottom side to facilitate springing the flange open against its resilient action when forced against the beaded rim 23 of the cup, followed by a camming of the rim 23 along the upper surface 32 under the pressure of the resilient force set up to urge the rim into the wedge shaped pocket between the surface 32 and the adjacent portion of the ftop 21. This pocket is formed with a wall 33 at its innermost corner recessed from the locus of the beaded rim 23 to permit the rim to become firmly wedged in the pocket and hence provide a tight and waterproof seal.

The yieldable resilience developed by this manner of forming the flange 22 is sufficient to enable the use of the invention for the small as well as the large sizes of commercially used containers.

The forming operation may be performed by any of the usual means known to the art, such as by the use of die presses and the device lends itself to the use of a single die press for the entire series of operations required.

After thus forming the flange, the lids may be provided with a wax or resin coating to increase the stiffness of the material. However, the resiliency of the lid does not depend upon such a coating as it is developed by the creases and folds entirely independent thereof.

Having thus described my invention, I claim:

1. A paper lid for a receptacle having an open top edge in the form of an annular beaded lip, said lid comprising a top circular portion adapted to overlie the lip and a dependent flanged portion substantially normal to and integral with the top portion, to surround and resiliently contact the lip, said flanged portion having circumferentially spaced radial creases extending thereabout, said portion in the creased condition being crushed endwise to provide a solid, relatively thick mass containing a multiplicity of random, discontinuous circumferential folds to retain the radial creases in a condition to impart circumferential resilience to the flanged portion.

2. The method of manufacturing a paper cup lid with a resilient holding flange comprising providing a series of radial creases spaced circumferentially on a marginal annular portion of a circular blank of stiff paper, then crushing Without rupturing the creased marginal portion endwise to provide a solid, relatively thick mass containing a multiplicity of random, discontinuous circumferential folds to retain the radial creases, the while positioning the marginal portion at right angles to the remaining portion of the blank.

References Cited in the tile of this patent UNITED STATES PATENTS 2,074,325 Carcw Mar. 23, 1937 2,614,727 Robinson Oct. 21, 1952 2,756,921 Sternau July 31, 1956 

